spfa

int dist[maxn],mp[maxn][maxn];
int visit[maxn];
void spfa()     //SPFA算法
{
    int i, now;
    memset(visit, false, sizeof(visit));
    for(i = 1; i <= n; i++) dist[i] = inf;
    dist[1] = 0;
    queue<int> Q;
    Q.push(1);
    visit[1] = true;
    while(!Q.empty())
    {
        now = Q.front();
        Q.pop();
        visit[now] = false;
        for(i = 1; i <= n; i++)
        {
            if(dist[i] > dist[now] + mp[now][i])
            {
                dist[i] = dist[now] + mp[now][i];
                if(visit[i] == 0)
                {
                    Q.push(i);
                    visit[i] = true;
                }
            }
        }
    }
}